SIOUX FALLS, S.D. - Tyrannosaurus rex may have been known as the big guy around the Hell Creek Formation 66 million years ago, but a newly discovered species of raptor would have roamed the region as one of its most lethal predators.

Dakotaraptor stood 6 feet tall at the hips yet moved like a springy, agile sprinter, reaching 30-40 mph, rivaling today’s ostrich. But potential prey caught admiring the 17-foot-long creature’s grace stood little chance, as the strong-muscled, winged Dromaeosaur boasted a vicious 91/2-inch-long killing claw that could make mincemeat out of any herbivore in its path, said Robert DePalma, curator of vertebrate paleontology at the Palm Beach Museum of Natural History.

“It had one of the strongest killing strokes in that slashing claw of any raptor known,” DePalma said.

DePalma and his research team including University of Kansas paleontologists announced the new species in a study published Oct. 30 by the University of Kansas Paleontological Institute. Dakotaraptor helps fill a gap in body size distribution between the small, birdlike Maniraptora creatures and the giant T. rex found in Hell Creek, which spans parts of northwestern South Dakota, southwestern North Dakota, eastern Montana and eastern Wyoming.

The newly discovered species roamed the earth alongside T. rex, the three-horned Triceratops and the duck-billed Edmontosaurus.

“Dakotaraptor coexisted with all of our favorites from our childhoods,” DePalma said. “We had no idea that such a cool and lethal creature existed right alongside them. And it was in the ground the whole time. It’s amazing.”

Thomas Holtz Jr., a senior vertebrate paleontology lecturer at the University of Maryland, said most of the raptor bones and teeth found in Hell Creek have been from small-form creatures.

“That is what is important about this find,” Holtz said. “In fact, it was rather bigger than most of us expected, almost the size of the largest known Dromaeosaurid, the much earlier Utahraptor.”

Dakotaraptor stands about as tall as Utahraptor, a species discovered in the 1990s in east-central Utah, but the raptors have completely different builds. The stockier Utahraptor, which lived about 60 million years earlier than Dakotaraptor, was an ambush predator with thicker bones and leg proportions that limited its speed, making it the “beefy bulldog of raptors,” DePalma said.

Robert DePalma, curator of vertebrate paleontology at the Palm Beach Museum of Natural History, examines the fierce foot claw of a newly discovered species of raptor called Dakotaraptor, on Oct. 29 in West Palm Beach, Fla.(Photo: Kylie Ruble/Robert DePalma/AP)

Dakotaraptor did not fly, which makes the presence of quill knobs on its arms especially interesting to DePalma and other dinosaur experts. The bumps serve as reinforcement points for long wing feathers, marking the first concrete evidence that large raptors had wings.

“It really would have made this like a turkey from hell,” he said.

The feathers were clearly not just for show, and they could have been used by the dinosaur to intimidate other predators, shield its young or as a tactical method to corral prey. They might also indicate that the species evolved from a lineage that once could fly or was evolving toward flight, DePalma said.

Dakotaraptor’s leg bones, wing portions, tail vertebrae, teeth and wishbone were unearthed in 2005 from a remote area of badlands in South Dakota’s Harding County.